ACE24C04.08A_11 Datasheet, PDF (9/15 Pages) ACE Technology Co., LTD. – Two-wire Serial EEPROM

ACE24C04/08A
Two-wire Serial EEPROM
Page Write
The 4/8K devices are capable of 16-byte page writes.
A page write is initiated the same as a byte write, but the microcontroller does not send a stop
condition after the first data word is clocked in. Instead, after the EEPROM acknowledges receipt of the
first data word, the microcontroller can transmit up to seven more data words. The EEPROM will
respond with a zero after each data word received. The microcontroller must terminate the page write
sequence with a stop condition (refer to Figure 9).
The data word address lower three bits are internally incremented following the receipt of each data
word. The higher data word address bits are not incremented, retaining the memory page row location.
When the word address, internally generated, reaches the page boundary, the following byte is placed
at the beginning of the same page. If more than eight data words are transmitted to the EEPROM, the
data word address will “roll over” and previous data will be overwritten.
Acknowledge Polling
Once the internally timed write cycle has started and the EEPROM inputs are disabled, acknowledge
polling can be initiated. This involves sending a start condition followed by the device address word.
The read/write bit is representative of the operation desired. Only if the internal write cycle has
completed will the EEPROM respond with a zero allowing the read or write sequence to continue.
Read Operations
Read operations are initiated the same way as write operations with the exception that the read/write
select bit in the device address word is set to one. There are three read operations: current address
read, random address read and sequential read.
Current Address Read
The internal data word address counter maintains the last address accessed during the last read or
write operation, incremented by one. This address stays valid between operations as long as the chip
power is maintained. The address “roll over” during read is from the last byte of the last memory page
to the first byte of the first page. The address “roll over” during write is from the last byte of the current
page to the first byte of the same page.
Once the device address with the read/write select bit set to one is clocked in and acknowledged by
the EEPROM, the current address data word is serially clocked out. The microcontroller does not
respond with an input zero but does generate a following stop condition (refer to Figure 10).
Random Read
A random read requires a “dummy” byte write sequence to load in the data word address. Once the
device address word and data word address are clocked in and acknowledged by the EEPROM, the
microcontroller must generate another start condition. The microcontroller now initiates a current
address read by sending a device address with the read/write select bit high. The EEPROM
acknowledges the device address and serially clocks out the data word. The microcontroller does not
respond with a zero but does generate a following stop condition (refer to Figure 11).
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